首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   25105篇
  免费   926篇
  国内免费   33篇
电工技术   335篇
综合类   41篇
化学工业   5694篇
金属工艺   383篇
机械仪表   480篇
建筑科学   1310篇
矿业工程   103篇
能源动力   629篇
轻工业   1930篇
水利工程   235篇
石油天然气   73篇
无线电   1851篇
一般工业技术   4541篇
冶金工业   4655篇
原子能技术   201篇
自动化技术   3603篇
  2023年   214篇
  2022年   359篇
  2021年   570篇
  2020年   340篇
  2019年   431篇
  2018年   541篇
  2017年   465篇
  2016年   633篇
  2015年   558篇
  2014年   763篇
  2013年   1432篇
  2012年   1170篇
  2011年   1519篇
  2010年   1091篇
  2009年   1028篇
  2008年   1151篇
  2007年   1092篇
  2006年   955篇
  2005年   770篇
  2004年   757篇
  2003年   671篇
  2002年   571篇
  2001年   440篇
  2000年   372篇
  1999年   412篇
  1998年   768篇
  1997年   565篇
  1996年   447篇
  1995年   422篇
  1994年   389篇
  1993年   370篇
  1992年   277篇
  1991年   196篇
  1990年   272篇
  1989年   265篇
  1988年   218篇
  1987年   231篇
  1986年   239篇
  1985年   273篇
  1984年   229篇
  1983年   231篇
  1982年   213篇
  1981年   201篇
  1980年   169篇
  1979年   197篇
  1978年   168篇
  1977年   196篇
  1976年   236篇
  1975年   161篇
  1974年   127篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Abstract

This article discusses different approaches to materiality and material expressions of cultural identity in contemporary Bahrain, a small Arab Gulf state. Various Islamic traditions have different understandings of materiality and its ontological qualities. In the contemporary Gulf this difference is often understood as a sectarian difference between Sunni and Shia Muslims, a division that has gained increasing political importance in recent years. In this article I discuss how these traditions view materiality in religion, in particular focusing on the role of material mediation for Shia Muslims, exemplified by the use and meaning of the turba prayer stone. With this as a point of departure I discuss two other forms of materiality—political graffiti and martyr images—that in the wake of the uprising in 2011 have also been imbued with sectarian meanings, but where this is less clear. I therefore argue that vernacular understandings of material culture show ambiguous identifications that challenge the clear dichotomies with which people—locally and analytically —often operate.  相似文献   
2.
We demonstrate that alkali-halide salts, particularly potassium bromide, can reduce the photothermal emission (PTE) from single walled carbon nanotubes (SWNT). PTE is a prominent spectral feature in Raman spectroscopy when a near infrared laser is used to analyze a dark colored sample. We subsequently show that trapping salts inside SWNT and coating SWNT with the salt has a more pronounced impact on not only reducing PTE, but also enhancing the intensity of the Raman spectral features. The effect, which we have called nanotube enhanced Raman spectroscopy (NERS), has differences and similarities to the widely studied surface enhanced Raman spectroscopy (SERS).  相似文献   
3.
In advancement of Pyrosil®‐technology a new kind of precursor delivery was developed, build and tested on real substrates. A Lab‐demonstrator was build to demonstrate the resources of the technology.  相似文献   
4.
Using an integrated process of data and modeling in HRA   总被引:1,自引:0,他引:1  
The paper describes an approach taken to estimate the probabilities of failure associated with various railroad tasks to prevent accidents (principally collisions and derailments). These probabilities were estimated using an expert elicitation process that used partially relevant data available from a variety of databases and that were filtered and scaled to make them more directly relevant to the analyses being performed. Extensive qualitative studies were performed prior to the elicitation process to identify relevant contexts under which the tasks can be performed.  相似文献   
5.
The probing of the micromechanical properties within a two‐dimensional polymer structure with sixfold symmetry fabricated via interference lithography reveals a nonuniform spatial distribution in the elastic modulus “imprinted” with an interference pattern in work reported by Tsukruk, Thomas, and co‐workers on p. 1324. The image prepared by M. Lemieux and T. Gorishnyy shows how the interference pattern is formed by three laser beams and is transferred to the solid polymer structure. The elastic and plastic properties within a two‐dimensional polymer (SU8) structure with sixfold symmetry fabricated via interference lithography are presented. There is a nonuniform spatial distribution in the elastic modulus, with a higher elastic modulus obtained for nodes (brightest regions in the laser interference pattern) and a lower elastic modulus for beams (darkest regions in the laser interference pattern) of the photopatterned films. We suggest that such a nonuniformity and unusual plastic behavior are related to the variable material properties “imprinted” by the interference pattern.  相似文献   
6.
The primary objective of this project is to identify gaps, whether real or perceived, that hinder effective groundwater management in New Zealand. These gaps show as gaps in information, gaps in implementation, gaps in technological and management tools, and gaps in understanding of fundamental processes. The secondary objective is to propose a management strategy to close the identified gaps. Several methods are used to meet these objectives: surveys distributed to selected staff in each regional council; the review of various written reports; the analysis of land-use databases; and private consultation within each regional council. Results show that groundwater management in New Zealand is generally reactionary with the main gaps being in strategic planning and national guidelines. Most gaps appear to be predominantly information and implementation issues. In some cases there are gaps in the understanding of fundamental processes within an aquifer system, including the long-term effects of land-use on groundwater quality. An adaptive management approach is suggested as a means of closing these gaps.  相似文献   
7.
A simple, yet realistic physics-based model is introduced to describe the subthreshold drain current of a MOSFET taking into account the body- and drain-voltage dependencies, including the short channel effects. This model, verified by SPICE simulations, describes adequately the pseudotriode and pseudosaturation regions of MOS transistors operated below V/sub T/. It can be applied for predicting bulk- or partially depleted (PD) SOI CMOS circuit operation. Analytical expressions derived for the logic switching threshold and delay are applied to predict the performance of CMOS-SOI inverters.  相似文献   
8.
In four-color fluorescence-based automated DNA sequencing, a 4×4 filter matrix parameterizes the relationship between the dye-intensity signals of interest and the data collected by an optical imaging system. The filter matrix is important because the estimated DNA sequence is based on the dye intensities that can only be recovered via inversion of the matrix. Here, the authors present a calibration method for the estimation of the columns of this matrix, using data generated through a special experiment in which DNA samples are labeled with only one fluorescent dye at a time. Simulations and applications of the method to real data are provided, with promising results  相似文献   
9.
The pipelined architecture and parallel organization of the AT&T Pixel Machine image computer are described and demonstrated with applications for the visualization of multidimensional fractals, particularly linear fractals and quaternion/ stacked Julia sets. Techniques for pushing the Pixel Machine to its peak abilities are described and apply to more recent parallel image computers as well.  相似文献   
10.
The purpose for this study was to evaluate the results of silicone oil use in patients who have undergone vitrectomy for proliferative vitreoretinopathy (PVR). The authors reviewed the 5-year results of 50 consecutive patients (52 eyes) with grade C1/D3 PVR operated on in 1987. Silicone oil has been removed in 42 eyes. The retina remained attached in 38 eyes. Visual acuities were finger counting in 12 eyes and 0.1 or greater in 19 eyes. Glaucoma was thought to be the major cause of loss of visual acuity after an initial improvement (9 eyes), as well as the most frequent complication of surgery (13 eyes). Silicone oil was deemed nonremovable in 10 operated eyes. A questionnaire was developed to determine the patients' perceptions of the use of silicone oil, and 46 patients responded to the questionnaire. Four patients indicated that they would not have elected to have surgery again. Six patients thought that surgery was not worthwhile, but would permit treatment again. Most patients thought that a modest amount of improvement had taken place and that vision was stable. Subjectively, most patients believed that surgery was worthwhile.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号